Heretofore, in an image forming apparatus which forms an image by an electrophotographic image forming method, so as to enhance a life of an apparatus, instead of a direct transfer method in which a toner image formed on an electrostatic latent image carrier such as a photoreceptor drum is directly transferred to an image support, investigated is an intermediate transfer method in which a toner image formed on an electrostatic latent image carrier is once transferred to an intermediate transfer belt (primary transfer), thereafter the toner image is transferred to the image support (secondary transfer) and fixed. Further, in view of downsizing, investigated is a method in which an intermediate transfer belt doubles as a function of conveying an image support.
Semi conductive belt is employed to the intermediate transfer belt. Specifically, for example, proposed is an intermediate transfer belt in which carbon black such as furnace black and acetylene black as conductive filler is dispersed in polyimide (Patent Documents 1-3).
However, in an environment of low temperature and low humidity, fine toner dots in white area may occur by an image forming apparatus using these intermediate transfer belts. Further, roughness of image may occur with long-term use.